Alert archive / New Jersey / Areal Flood Warnings in 2021

Areal Flood Warning 21, NWS Philadelphia/Mount Holly

August 22, 2021Hunterdon County, Mercer County, Monmouth County, New Jersey

NWS Philadelphia/Mount Holly issued this areal flood warning at Aug 22, 2021, 10:52 AM EDT for Hunterdon County, Mercer County, Monmouth County, New Jersey. It was in force for 13 hr. 6 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 22, 2021, 10:52 AM EDT (14:52 UTC)
Expired
Aug 23, 2021, 12:00 AM EDT
In force
13 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Hunterdon County, NJ, Mercer County, NJ, Monmouth County, NJ

The radar

The Philadelphia radar (KDIX), 42 km from the middle of the area, began a volume at 14:54 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
Aug 22, 11:00 AM EDTHEAVY RAIN 1.35Washington Crossing, PAMESONET STATION WASN4 WASHINGTON CROSSING.
Aug 22, 11:30 AM EDTFLOOD2 Sw Princeton, NJTHE GAUGE ON STONY BROOK AT PRINCETON REACHED MINOR FLOOD STAGE.
Aug 22, 11:30 AM EDTHEAVY RAIN 4.370.7 Ne Haminton Square, NJ
Aug 22, 11:59 AM EDTHEAVY RAIN 1.132 Ssw Ewing, NJMESONET STATION TRSLV TRENTON (VILLAGE CH.).
Aug 22, 2:15 PM EDTFLOODPrinceton Junction, NJGROVERS MILL POND IN WEST WINDSOR TOWNSHIP OVERFLOWING ACROSS CLARKSVILLE ROAD. ROADWAY IS CLOSED.
Aug 22, 5:00 PM EDTFLOOD1 E North Princeton, NJFLOODING ON NJ 27 NORTHBOUND SOUTH OF CR 605/RIVER RD (PRINCETON TWP) TO CR 605/RIVER RD (PRINCETON TWP) ALL LANES CLOSED AND DETOURED.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 2.9 hours before the alert went out and 165 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Brookhaven, NY at 12:00Z on 2021-08-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 36 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Brookhaven, NY at 12:00Z on 2021-08-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 130 square meters per square second.193958Sfc1 km3 km6 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
36 J/kg
Mixed-layer CIN
-3 J/kg
Mixed-layer LCL
563 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
130 m²/s²
0-3 km storm-relative helicity
163 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

As transmitted.

655 
WGUS41 KPHI 221452
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
1052 AM EDT Sun Aug 22 2021

NJC019-021-025-222100-
/O.NEW.KPHI.FA.W.0021.210822T1452Z-210822T2100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Mercer NJ-Monmouth NJ-
1052 AM EDT Sun Aug 22 2021

The National Weather Service in Mount Holly has issued a

* Flood Warning for...
  Mercer County in central New Jersey...
  Southwestern Monmouth County in central New Jersey...
  Southeastern Hunterdon County in northwestern New Jersey...

* Until 500 PM EDT Sunday.

* At 1052 AM EDT, local law enforcement reported flooding in the 
  warned area. Several road closures remain, especially in Mercer 
  and Monmouth Counties. Flooding is already occurring. Between 3 
  and 9 inches of rain have fallen.

* For Assunpink Creek at Trenton:
  At 10:15am the stage was 7.72 feet.
  Flood Stage is 8.5 feet.
  ...
  For Stony Brook at Princeton:
  At 10:30am the stage was 8.14 feet.
  Flood Stage is 9 feet.
  ...
  For Assunpink Creek at Mercerville:
  At 10:30am the stage was 8.23 feet.
  Flood Stage is 9.5 feet.
  ...
  For Assunpink Creek at Clarksville:
  At 10:00am the stage was 6.58 feet.
  Flood Stage is 8 feet.

This includes the following highways...
	New Jersey Turnpike between exits 8 and 8A.
	Interstate 295 in New Jersey between mile markers 59 and 76.
	Interstate 195 in New Jersey between mile markers 0 and 16.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around...don't drown when encountering flooded roads. Most 
flood deaths occur in vehicles.

&&

LAT...LON 4034 7494 4047 7492 4043 7475 4038 7472
      4039 7465 4038 7462 4032 7462 4027 7448
      4025 7448 4024 7425 4017 7428 4017 7441
      4008 7455 4014 7459 4018 7471 4015 7472
      4022 7477 4025 7484 4030 7487

$$

CMS
2 follow-up statements
908 
WGUS81 KPHI 221640
FLSPHI

Flood Statement
National Weather Service Mount Holly NJ
1240 PM EDT Sun Aug 22 2021

NJC019-021-025-222100-
/O.CON.KPHI.FA.W.0021.000000T0000Z-210822T2100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Mercer NJ-Monmouth NJ-
1240 PM EDT Sun Aug 22 2021

...FLOOD WARNING REMAINS IN EFFECT UNTIL 5 PM EDT THIS AFTERNOON FOR 
MERCER, SOUTHWESTERN MONMOUTH, AND SOUTHEASTERN HUNTERDON COUNTIES...

At 1240 PM EDT, gauge reports indicated creeks and streams were 
elevated or in flood across the warning area. Stony Brook at 
Princeton is in minor flood at this time. Meanwhile, law enforcement 
continues to report several road closures across the area. Do not 
drive through flooded roadways!

For Stony Brook at Princeton:
At 11:30am the stage was 9.0 feet.
Flood Stage is 9 feet.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around...don't drown when encountering flooded roads. Most 
flood deaths occur in vehicles.

&&

LAT...LON 4034 7494 4047 7492 4043 7475 4038 7472
      4039 7465 4038 7462 4032 7462 4027 7448
      4025 7448 4024 7425 4017 7428 4017 7441
      4008 7455 4014 7459 4018 7471 4015 7472
      4022 7477 4025 7484 4030 7487

$$

CMS
042 
WGUS41 KPHI 221948
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
348 PM EDT Sun Aug 22 2021

NJC019-021-025-230400-
/O.EXT.KPHI.FA.W.0021.000000T0000Z-210823T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hunterdon NJ-Mercer NJ-Monmouth NJ-
348 PM EDT Sun Aug 22 2021

The National Weather Service in Mount Holly has extended the

* Flood Warning for...
  Mercer County in central New Jersey...
  Southwestern Monmouth County in central New Jersey...
  Southeastern Hunterdon County in northwestern New Jersey...

* Until midnight EDT Monday.

* At 348 PM EDT, gauge reports indicated flooding continues in 
  creeks and streams in Mercer, Hunterdon, and Monmouth Counties. 
  Stony Brook in Princeton remains in moderate flood at this time. 
  In addition, several roads remain closed from flash flooding that 
  occurred last night. Never drive across flooded roadways!

* For Stony Brook at Princeton:
  At 2:30pm the stage was 12.16 feet.
  Flood Stage is 9 feet.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around...don't drown when encountering flooded roads. Most 
flood deaths occur in vehicles.

&&

LAT...LON 4034 7494 4047 7492 4043 7475 4038 7472
      4039 7465 4038 7462 4032 7462 4027 7448
      4025 7448 4024 7425 4017 7428 4017 7441
      4008 7455 4014 7459 4018 7471 4015 7472
      4022 7477 4025 7484 4030 7487

$$

CMS

The office that day

Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 21, 9:35 PM EDTAreal Flood AdvisoryPHIMercer, Middlesex, Monmouth, Ocean3 hr
Aug 21, 10:47 PM EDTAreal Flood AdvisoryPHIMorris3 hr
Aug 21, 11:38 PM EDTAreal Flood AdvisoryPHIAtlantic, Burlington, Monmouth, Ocean3 hr
Aug 22, 12:04 AM EDTAreal Flood AdvisoryPHIAtlantic, Burlington, Camden, Monmouth, Ocean3 hr
Aug 22, 12:24 AM EDTFlash Flood WarningPHIMorris3 hr
Aug 22, 1:30 AM EDTAreal Flood AdvisoryPHIMiddlesex, Monmouth4 hr
Aug 22, 1:35 AM EDTAreal Flood AdvisoryPHIMorris, Somerset3 hr
Aug 22, 2:04 AM EDTFlash Flood WarningPHIMiddlesex, Monmouth9 hr
Aug 22, 2:09 AM EDTFlash Flood WarningPHIBurlington, Ocean5 hr
Aug 22, 2:40 AM EDTFlash Flood WarningPHIHunterdon, Morris, Somerset5 hr
Aug 22, 3:10 AM EDTFlash Flood WarningPHIBurlington, Hunterdon, Mercer, Monmouth, Ocean8 hr
Aug 22, 4:21 AM EDTFlash Flood WarningPHIMonmouth, Ocean3 hr
Aug 22, 5:36 AM EDTFlash Flood Warning Considerable damage threatPHIMercer, Middlesex, Monmouth, Somerset5 hr
Aug 22, 6:07 AM EDTFlash Flood WarningPHIHunterdon, Warren67 min
Aug 22, 7:52 AM EDTAreal Flood WarningPHIHunterdon, Somerset15 hr
Aug 22, 10:43 AM EDTSpecial Marine WarningPHI62 min
Aug 22, 10:49 AM EDTAreal Flood WarningPHIMiddlesex, Monmouth, Somerset13 hr
Aug 22, 11:06 AM EDTSpecial Marine WarningPHI54 min
Aug 22, 1:35 PM EDTCoastal Flood AdvisoryPHICape May10 hr
Aug 22, 1:53 PM EDTAreal Flood AdvisoryPHIMorris6 hr
Aug 22, 3:21 PM EDTRiver Flood WarningPHISomerset54 hr
Aug 22, 5:07 PM EDTAreal Flood AdvisoryPHIMorris, Sussex, Warren6 hr
Aug 22, 5:48 PM EDTFlash Flood WarningPHIMorris, Sussex, Warren6 hr

Nearby

Areal Flood Warnings in New Jersey, 2021Every areal flood warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.